Air Force space plane in Earth orbit for over 400 days.
Credit: Boeing

The U.S. Air Force’s X-37B Orbital Test Vehicle 4 is seen after landing at NASA ‘s Kennedy Space Center Shuttle Landing Facility in Florida on May 7, 2017.
Credit: U.S. Air Force courtesy photo

 

The hush-hush mission of a U.S. Air Force X-37B mini-space plane has winged past 400 days of flight.

This mission – tagged as Orbital Test Vehicle (OTV-5) — was rocketed into Earth orbit on September 7, 2017 atop a SpaceX Falcon 9 booster from Launch Complex 39A at NASA’s Kennedy Space Center in Florida.

The robotic winged drone is carrying out secretive duties during the program’s fifth flight.

Flight duration

Each X-37B/OTV mission has set a new flight-duration record for the program:

OTV-1 began April 22, 2010, and concluded on Dec. 3, 2010, after 224 days in orbit.

OTV-2 began March 5, 2011, and concluded on June 16, 2012, after 468 days on orbit.

OTV-3 chalked up nearly 675 days in orbit before finally coming down on Oct. 17, 2014.

OTV-4 conducted on-orbit experiments for 718 days during its mission, extending the total number of days spent in space for the OTV program at that point to 2,085 days.

Asets-II payload logo.
Credit: AFRL

What’s up?

On this latest clandestine mission of the space plane, all that’s known according to Air Force officials is that one payload flying on OTV-5 is the Advanced Structurally Embedded Thermal Spreader, or ASETS-II.

Developed by the U.S. Air Force Research Laboratory (AFRL), this cargo is testing experimental electronics and oscillating heat pipes for long duration stints in the space environment. According to AFRL, the three primary science objectives are to measure the initial on-orbit thermal performance, to measure long duration thermal performance, and to assess any lifetime degradation.

The X-37B Orbital Test Vehicle mission 4 (OTV-4), the Air Force’s unmanned, reusable space plane, landed at NASA’s Kennedy Space Center Shuttle Landing Facility May 7, 2017.
Credit: USAF

Landing site

When the space plane will land is unknown. The last Air Force’s X-37B Orbital Test Vehicle mission touched down at NASA’s Kennedy Space Center Shuttle Landing Facility May 7, 2017 – a first for the program. All prior missions had ended with a tarmac touchdown at Vandenberg Air Force Base in California.

Several website postings say that the sixth mission, X-37B OTV-6, is planned for 2019 on a United Launch Alliance Atlas-5(501) rocket. Launch would be from Cape Canaveral Air Force Station’s Space Launch Complex-41.

Credit: Illustration by Giuseppe De Chiara

 

Reusable vehicles

The classified X-37B program “fleet” consists of two known reusable vehicles, both of which were built by Boeing. The X-37B Orbital Test Vehicle was built at several Boeing locations in Southern California, including Huntington Beach, Seal Beach and El Segundo. The program transitioned to the U.S. Air Force in 2004 after earlier funded research efforts by Boeing, NASA and the Defense Advanced Research Projects Agency.

Looking like a miniature version of NASA’s now-retired space shuttle orbiter, the military space plane is 29 feet (8.8 meters) long and 9.6 feet (2.9 m) tall, with a wingspan of nearly 15 feet (4.6 m). The X-37B space plane has a payload bay of 7 feet (2.1 meters) by 4 feet (1.2 meters), a bay that can be outfitted with a robotic arm. X-37B has a launch weight of 11,000 lbs. (4,990 kilograms) and is powered on orbit by gallium-arsenide solar cells with lithium-ion batteries.

Back to hangar for another flight day. U.S. Air Force X-37B/OTV-4 is rolled into facility after its May 7 landing at Kennedy Space Center.
Credit: Michael Martin/SAF

On-orbit duties

The missions of the X-37B space planes are carried out under the auspices of the Air Force Rapid Capabilities Office, and mission control for OTV flights are handled by the 3rd Space Experimentation Squadron at Schriever Air Force Base in Colorado. This squadron oversees operations of the X-37B Orbital Test Vehicle.

This Schriever Air Force Base unit is billed as the Air Force Space Command’s premier organization for space-based demonstrations, pathfinders and experiment testing, gathering information on objects high above Earth and carrying out other intelligence-gathering duties.

And that may be a signal as to what the robotic craft is doing — both looking down at Earth and upward.

Repeating ground tracks

Ted Molczan, a Toronto-based satellite analyst, told Inside Outer Space that OTV 5’s orbit at the start of August was about 197 miles (317 kilometers) high, inclined 54.5 deg to the equator. Its ground track repeated nearly every five days, after 78 revolutions.

“Maneuvers on August 18 and 21 raised its orbit by 45 miles (74 kilometers) which caused its ground track to exactly repeat every three days, after 46 revolutions. It was still in that orbit when last observed, on September 8, by Alberto Rango, from Rome, Italy,” Molczan added.

“Repeating ground tracks are very common,” Molczan said, “especially for spacecraft that observe the Earth. I do not know why OTV has repeating ground tracks,” he concluded.

 

Leave a Reply

Griffith Observatory Event